Here’s the blippoo box patch we shared on social media this week!
What is the blippoo box? Benjolin? Rungler?
The late Rob Hordijk was a brilliant synth designer. His methodology of creating instruments was based on the idea of putting together a singular fixed patch with very musical modulation sources and allowing the user to navigate this terrain. One of his best designs, the Blippoo Box is emulated in this patch.
The benjolin oscillator is two triangle core oscillators whose frequencies are controlled by a circuit he calls the “rungler.” A rungler is simply a shift register with two triangle wave oscillators fed into it. The loop of the shift register can be locked to 8 steps or 16 steps. What makes this circuit unique is that rob added an attenverter for each oscillator with the rungler being fed into it - this creates a chaotic feedback network.
Chaos is different than true random; in a chaotic network, random signals can get locked in stasis where a pattern starts to arrive out of the randomness. Locking and unlocking the shift register helps create this stasis. The rungler signal in its own right becomes a pseudo melody & pattern machine.
The “Twin Peak Filter” concept Hordijk introduced in the Blippoo Box is two 18db per octave lowpass filters that are subtracted from one another. Subtracting two lowpass filters from one another creates a strange dual peak bandpass filter which creates all kinds of phasing and notching sounds. In many clones of the blippoo box or benjolin, these filters have a fixed spacing and are controlled by a single frequency knob. The original blippoo box did not operate in this fashion - it had dedicated filter cutoffs for each filter.
I like to use the XOR output of the benjolin to feed the twin peak filter. The XOR output creates logic gates derived from the two oscillators and are excellent for pinging resonant filters. The resonant filters now become pseudo-oscillators with a natural sounding decay, almost reminiscent of a resonant lowpass gate.
Long story short, twist all the knobs and make really psychotic bubbling textures!
External audio path:
-Main audio output on channel 1.
Internal audio path:
-Benjolin XOR output is routed to two parallel resonant lowpass filters
-Each lowpass filter is subtracted from one another to create the Hordijk “twin peak” filter
-The output of the filter mixer feeds into a brick wall limiter to smooth out the extreme dynamics of the patch
-The entire patch is then fed into a master spring reverb
Internal CV Path:
-The rungler output of the Benjolin oscillator is controlling the cutoff frequency of both filters
MetaModule knob mappings:
A - Benjolin oscillator 1 frequency
B - Benjolin oscillator 2 frequency
C - Benjolin rungler 1 amount
D - Benjolin rungler 2 amount
E - Rungler pattern lock
F - Spring reverb dry/wet
U - Filter 1 cutoff
V - Filter 1 resonance
W - Filter 1 attenuverter
X - Filter 2 cutoff
Y - Filter 2 resonance
Z - Filter 2 attenuverter
Blippoo box.vcv (2.2 KB)
Blippoo Box.yml (6.8 KB)